1. Field of the Invention
This invention relates to a movement detection and control device and, more particularly, to a movement detection and control device for detecting and controlling movement of a lens frame driven by a driving source.
2. Related Background Art
In a camera or equivalent apparatus for taking photographs, various proposals have been made and also put into practice in the past with respect to a mechanism and the like for automatically providing focus adjustment, exposure adjustment, and so forth.
For example, an exposure and focus adjustment device in a camera as disclosed in the published Japanese Utility Model Application Examined No. 5-31609 is constructed to permit the driving force of a rotational driving source (motor) to be selectively transmitted to a focus-adjusting mechanism and an exposure-adjusting mechanism via a differential gear mechanism. The above device is provided with a pulse-generating device, an AF switch, an AE switch, and so forth in order that unidirectional rotation of the motor provides driving in a controlled manner. The pulse-generating device is formed by both a mask plate having a plurality of slits and a photo-interruptor, thereby generating a pulse signal. The AF switch takes off a positional signal of a gear for automatic focusing from the pulse signal. The AE switch takes off a positional signal of a gear for automatic exposure from the pulse signal.
In addition, a lens mount disclosed in the published Japanese Patent Application Unexamined No. 6-242484 is a lens mount with a shutter device. The lens mount is provided with a photo-interruptor for automatic focusing, a photo-interruptor for automatic exposure, and so forth in order that bidirectional rotation of a motor provides driving in a controlled manner. The former photo-interruptor measures a moving distance of a gang of focusing lenses, while the latter photo-interruptor detects movement of a shutter vane-driving lever. The shutter vane-driving lever is driven by a plunger solenoid-driving device, and drives a shutter vane.
Turning back to the foregoing Application No. 5-31609, since a means disclosed therein requires a switch for taking off the positional signal, there exists a problem of an increase in manufacturing cost.
With further reference to the foregoing Application No. 6-242484, a means disclosed therein includes a cam ring for moving the gang of focusing lenses. The cam ring is once reversed at an initial step by the motor being rotated in one direction, whereby the cam ring is brought into abutting contact with a stopper. This state is set to be an initial position of the cam ring. The cam ring is thereafter brought into normal rotation from the initial position by the motor being rotated in the other direction. As a result, focusing drive is effected, while the photo-interruptor for automatic focusing is caused to provide detection. In short, bidirectional rotation of the motor provides driving in a controlled manner. This results in a complicated motor control circuit and a complicated sequence and the like, which may add to manufacturing costs.